package medium.array;

import java.util.ArrayList;
import java.util.List;

/**
 * <a href="https://leetcode-cn.com/problems/spiral-matrix">54. 螺旋矩阵</a>
 * 给你一个 m 行 n 列的矩阵 matrix ，请按照 顺时针螺旋顺序 ，返回矩阵中的所有元素。
 * 示例 1：
 *   输入：matrix = [[1,2,3],[4,5,6],[7,8,9]]
 *   输出：[1,2,3,6,9,8,7,4,5]
 * 示例 2：
 *   输入：matrix = [[1,2,3,4],[5,6,7,8],[9,10,11,12]]
 *   输出：[1,2,3,4,8,12,11,10,9,5,6,7]
 * 提示：
 *   m == matrix.length
 *   n == matrix[i].length
 *   1 <= m, n <= 10
 *   -100 <= matrix[i][j] <= 100
 * @author 刘学松
 * @date 2021-03-15 20:02
 */
public class 螺旋矩阵 {
    public List<Integer> spiralOrder(int[][] matrix) {
        List<Integer> list = new ArrayList<>();
        int left = 0, top = 0;
        int right = matrix[0].length-1, bottom = matrix.length-1;

        while (left <= right && top <= bottom) {
            for (int i = left; i <= right; i++) {
                list.add(matrix[top][i]);
            }
            top++;

            for (int i = top; i <= bottom; i++) {
                list.add(matrix[i][right]);
            }
            right--;

            for (int i = right; i >= left; i--) {
                list.add(matrix[bottom][i]);
            }
            bottom--;

            for (int i = bottom; i >= top; i--) {
                list.add(matrix[i][left]);
            }
            left++;
        }
        return list;
    }
}
